Top Angular Interview Questions and Answers

Here are top Angular interview questions, 

1. What is Angular?

Angular is a popular open-source front-end framework developed by Google. It is used to build dynamic, single-page web applications (SPAs) and provides tools for building reusable components, managing data, and handling user interactions.

 

2. What are the key features of Angular?

   - Two-way data binding

   - Directives for extending HTML syntax

   - Dependency injection

   - Routing and navigation

   - Templating and views

   - Reactive forms and validation

   - HTTP client for server communication

 

3. What is the difference between AngularJS and Angular?

   - AngularJS (Angular 1.x): The first version of Angular, based on MVC architecture and uses JavaScript. It is no longer actively developed.

   - Angular (Angular 2+): The modern version of Angular, based on a component-based architecture and uses TypeScript. It introduced significant improvements in performance and maintainability.

 

4. Explain the concept of modules in Angular.

Modules in Angular are containers for organizing components, services, directives, and other building blocks of an application. They help in modularizing and organizing the codebase.

 

5. What are decorators in Angular?

Decorators are functions that modify classes, methods, or properties. In Angular, decorators are used for various purposes, such as defining components, services, directives, etc.

 

6. What is data binding in Angular?

Data binding is a mechanism that synchronizes the data between the component and the template. Angular supports two-way data binding, where changes in the component are automatically reflected in the view and vice versa.

 

7. Explain the difference between template-driven forms and reactive forms in Angular.

   - Template-driven forms: Simple form implementation using Angular's template syntax. The form structure is defined in the template itself.

   - Reactive forms: More flexible and scalable approach using form model objects. The form structure is defined programmatically in the component.

 

8. What is a directive in Angular?

A directive is a class with a `@Directive` decorator that can change the behavior or appearance of an element in the DOM.

 

9. What are services in Angular, and how are they used?

Services are classes in Angular that provide specific functionality and can be injected into components or other services. They help in separating concerns and promoting code reusability.

 

10. What is Angular CLI?

Angular CLI (Command Line Interface) is a powerful command-line tool that helps with scaffolding, building, testing, and deploying Angular applications. It provides various commands to streamline the development process.

 

11. What is lazy loading in Angular?

Lazy loading is a technique used to load Angular modules on-demand, rather than loading everything upfront. It helps improve application performance by reducing the initial loading time.

 

12. Explain Angular component lifecycle hooks.

Angular component lifecycle hooks are methods that are called at different stages of a component's lifecycle, such as `ngOnInit`, `ngOnChanges`, `ngAfterViewInit`, etc. They allow you to perform actions at specific points in the component's life.

 

13. What is Angular router outlet?

The router outlet is a directive used to mark the location in the template where Angular router will render the view of the matched component based on the URL.

 

14. How do you handle HTTP requests in Angular?

Angular provides the `HttpClient` module for making HTTP requests to the server. You can use methods like `get`, `post`, `put`, `delete`, etc., to interact with APIs.

 

15. What are Angular guards?

Angular guards are used to protect routes in an application. They can prevent unauthorized access to certain routes or perform certain actions before loading a route.

 

16. What is Angular ngFor directive used for?

The `ngFor` directive is used for looping through a collection in the template and rendering elements multiple times based on the collection's data.

 

17. Explain the concept of dependency injection in Angular.

Dependency injection is a design pattern used in Angular to provide dependencies to a class or component from an external source. It helps in creating loosely coupled and testable code.

 

18. How do you handle errors in HTTP requests in Angular?

You can use the `catchError` operator in the `HttpClient` module to handle errors in HTTP requests and provide fallback actions or error messages.

 

19. What are Angular pipes?

Pipes are used for transforming data in the template before displaying it. Angular provides built-in pipes like `date`, `uppercase`, `currency`, etc., and you can create custom pipes as well.

 

20. How can you communicate between parent and child components in Angular?

You can use `@Input()` to pass data from the parent to the child component and `@Output()` with `EventEmitter` to emit events from the child to the parent component.

 

Above are few top Angular interview questions. Remember to prepare and expand on these answers.

Good luck with your interview! 👍